How to take PrEP
There are 2 different ways of taking PrEP. You can take a pill every day or you can take it only when you need it. Taking PrEP only when you need to is called on-demand or event-based PrEP. Both ways of taking PrEP are safe and effective.
You can start PrEP by taking 2 pills on your first day. This double dose protects you within 2 hours.
Daily PrEP - 1 pill a day
Taking PrEP daily means you have continued protection, even when you do not have sex. It means you can have sex anytime without needing to plan.
Start by taking 2 pills on your first day. Then take 1 pill every day.
You can take the pill at any time of day, but it’s easier to remember if you take it around the same time every day.
On-demand PrEP
On-demand or event-based PrEP means only taking PrEP when you need it. There are 2 ways of doing this, known as 2:1:1 dosing and 2:7 dosing.
With event-based PrEP, you really need to take all the pills at the right times. And you need to know ahead of time that you might have sex so you can start the medication.
Do not use on-demand PrEP if you have hepatitis B or if you’ve ever had hepatitis B. PrEP can affect the hepatitis B virus. Starting and stopping PrEP can cause a flare-up in symptoms and lead to liver inflammation.
2:1:1 dosing
Suitable if you only have anal sex, or if you use your penis during penetrative vaginal or anal sex.
To use 2:1:1 PrEP:
take 2 pills, 2 to 24 hours before having sex
after sex, take 1 tablet every 24 hours until you’ve had 2 days without having sex
2:7 dosing
Suitable if you’re using your vagina, neovagina or front hole during penetrative sex.
To use 2:7 PrEP:
take 2 pills, 2 to 24 hours before having sex
after sex, take 1 tablet every 24 hours for 7 days
What to do if you miss a pill
For daily PrEP
If you’ve been taking PrEP every day for at least a week and you miss a pill, your PrEP will still work and you’ll be protected. You should take your missed pill as soon as you remember, if it’s within 12 hours of when you were supposed to take it.
If more than 12 hours have passed, skip the dose and take the next tablet at the usual time.
With daily PrEP, missing a pill occasionally will not affect your level of HIV protection, as long as you have taken at least 4 days of PrEP a week for having anal sex or 6 days of PrEP a week for vaginal or frontal sex.
For on-demand PrEP
With on-demand and event-based PrEP, there’s less medication in your body so it’s more important that you take all the doses on time.
If you forget an on-demand dose, take it as soon as you remember
If you missed the 2 pills you take before sex take them as soon as you can, even if it is after sex, then continue with the daily single pills
Contact your clinic or doctor immediately to find out if you need additional protection from PEP. It’s best to start PEP within 24 hours of sex, but you can start it up to 72 hours after.
If you find that you often miss a dose, you might get better protection from taking daily PrEP.
Daily or on-demand - how to choose?
If both methods are suitable for you, you can choose which best suits you and your needs. You can also change between methods if they suit different times in your life.
Daily PrEP can be easier to remember, as you get into a routine. Some people find it helps reduce the side effects they experience as well. It’s also good if you do not want to plan ahead for when you might have sex.
On-demand PrEP can be good for times when you know you’re not having sex that often, or you do not need the protection of PrEP all the time.
If you’re thinking about on-demand PrEP, you need to feel comfortable that:
you generally do remember to take pills on time
you can have at least 2 hours of lead-in time before having sex, so you know when you take the first pills
you’re ok with the slightly more complicated schedule of on-demand PrEP
you do not have and have never had hepatitis B
Stopping PrEP
Whether you’re taking a break from PrEP because your sex life has changed or you want to stop the medication completely, you need to make sure that you’ve taken enough PrEP to protect you after your most recent condomless sex.
If you’re taking daily PrEP, you’ll need to take PrEP for 7 days after condomless sex and then stop.
If you’re taking PrEP on-demand, you need to take the last planned dose for after sex. This would be after 2 daily pills if you do 2-1-1 or 7 daily pills if you do 2:7.
We recommend you do a HIV test 6 weeks after the last time you had sex.
If you’re worried that you’ve had contact with HIV at any time after you’ve stopped PrEP, you may need to consider PEP. You can contact your local clinic to find out more.
If you want to restart PrEP at any time, you will need to have a HIV test and you might need to have a kidney function test before PrEP can be prescribed.
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